1. Field of the Invention
The present invention relates to a printer, and more particularly, it relates to a printer having a temperature sensor chip.
2. Description of the Background Art
An electronic apparatus having a thermistor (temperature sensor) for sensing a temperature is known in general, as disclosed in Japanese Patent Laying-Open No. 10-48057 (1998), for example.
The electronic apparatus disclosed in the aforementioned Japanese Patent Laying-Open No. 10-48057 is provided with a thermistor for sensing the temperature of a power transistor element itself. In this electronic apparatus, a wiring pattern of the power transistor is partially widened and the thermistor is so mounted on a substrate that an element portion thereof is in close contact with the wide portion of the wiring pattern, whereby the thermistor can sense the temperature of the power transistor element itself through a wire. In the electronic apparatus disclosed in the aforementioned Japanese Patent Laying-Open No. 10-48057, however, the thermistor must be mounted on a hole of the substrate by soldering or the like, and hence manufacturing steps for the electronic apparatus is disadvantageously complicated.
In this regard, there is proposed an electronic apparatus provided with a chip-type thermistor (temperature sensor chip) allowing surface mounting, which is a system of mounting the thermistor on the surface of a substrate or the like by fitting the former into the latter. For example, Japanese Patent Laying-Open No. 11-307308 (1999) or 2005-43162 proposes this type of electronic apparatus.
The electronic apparatus proposed in the aforementioned Japanese Patent Laying-Open No. 11-307308 is provided with a chip-type thermistor (temperature sensor chip) formed on its lower portion with a projecting portion fittable into a substrate. This chip-type thermistor is so fitted into the substrate that a step of mounting the same on the substrate can be simplified. Further, the projecting portion is so provided on the lower portion of this chip-type thermistor as to come into contact with the substrate, whereby heat is easily conducted from the substrate to the chip-type thermistor. Thus, the chip-type thermistor according to Japanese Patent Laying-Open No. 11-307308 can sense the temperature of the substrate.
The electronic apparatus proposed in the aforementioned Japanese Patent Laying-Open No. 2005-431562 is provided with a diode whose temperature is to be sensed and a chip-type thermistor (temperature sensor chip) fittable into a substrate for sensing the temperature of the diode. This chip-type thermistor is so fitted into the substrate that a step of mounting the same on the substrate can be simplified. In this electronic apparatus according to Japanese Patent Laying-Open No. 2005-431562, first terminals of the thermistor and the diode are connected with each other through a conductor pattern grounded to the same ground pattern (not shown). Heat is transmitted from the diode to the thermistor through the conductor pattern, so that the thermistor senses the heat. Japanese Patent Laying-Open No. 2005-431562 also discloses a technique of improving conductivity of the heat from the diode to the thermistor by increasing the width of the conductor pattern.
On the other hand, a printer provided with a temperature sensor chip for sensing the internal ambient temperature of a printer body is proposed in general. In this printer, the temperature sensor chip and another electronic component such as a supply circuit are grounded to a common ground pattern provided over the entire region of a wiring board.
In the aforementioned conventional printer provided with the temperature sensor chip for sensing the internal ambient temperature of the printer body, however, a power supply component and the temperature sensor chip are grounded to the common ground pattern and hence heat is conducted from the power supply component or the like to the temperature sensor chip through the ground pattern. Therefore, the temperature sensor chip is so easily influenced by the heat of the power supply component or the like that it is difficult to correctly sense the internal ambient temperature of the printer body with the temperature sensor chip.
When the technique of the aforementioned Japanese Patent Laying-Open No. 11-307308 is applied to the temperature sensor chip sensing the internal ambient temperature of the body of the aforementioned conventional printer, the lower surface of the temperature sensor chip so comes into contact with the substrate that heat is easily transmitted from the substrate to the thermistor. Also in this case, therefore, the temperature sensor chip is so easily influenced by the heat of the substrate that it is difficult to correctly sense the internal ambient temperature of the printer body.
When the technique of the aforementioned Japanese Patent Laying-Open No. 2005-431562 is applied to the temperature sensor chip sensing the internal ambient temperature of the body of the aforementioned conventional printer, heat is easily conducted from the power supply component to the temperature sensor chip through the conductor pattern whose width is increased for improving heat conductivity. Also in this case, therefore, the temperature sensor chip is so easily influenced by the heat of the power supply component or the like that it is difficult to correctly sense the internal ambient temperature of the printer body.